Didn't Wharfedale also do a LvR demonstration? Thought I remember reading about it maybe even at Carnegie Hall?
Yes, I have a copy of a writeup from the Aug. 1955 Hi Fidelity.
"Very good but not versimiltude is, in fact, the over-all judgement for the session as a whole. Mr. Briggs had live harpsichord, piano, organ, and chorus on hand for test matching. The harpsichord in reproduction was excellent, just a bit short of perfect. The Wharfedale version of a piano was beautiful sound, but lacked the brightness and full sonority of a real Steinway heard a moment later, even in works calling for no great weight of piano tome. The organ matched well, when lighter registration was used, but no effort was made to match the speakers against a real thirty foot pipe."
This was in London's royal Festival Hall, a large (3000 people) hall known for its dead acoutics. Amazing that they could get the level from a number of Quad 15 watt amps.
The main event was a playback of a master tape of the BBC Symphony and chorus: "Certainly the effect was different from that of a chorus and orchestra on the stage, but the large masses of sound were full, spacious, and (the hardest thing of all) produced without apparent distortion or strain."
Briggs also played back a selection of commercial LPs.
While looking for this one I ran across another one from 1955 where 4000 seat Constitution Hall in D.C. was used. They actually recorded a symphony orchestra as it played and then played it back right after. The speakers were Jensen Imperials, a large horn loaded system. "The balance was rich and full. There was no doubt that it was recorded sound, but it was good recorded sound."
Reproducing an orchestra would, of course, require considerably more acoustic output.
Yet another one was the Bell Telephones Auditory Perspectives series which was famous for exploring 2 and 3 channel stereo playback in the early 1930s. In one demonstration they had an orchestra in an upstairs hall playing back downstairs in the primary concert hall. They also use phone lines to send the 3 channels from Philadelphia to Washington for another demonstration. The article talks about the you-are-there, they-are-here choice and also the need to record the orchestra fairly close, although they found the 3 channel reproduction better when they recorded from a little farther back. The playback system was a trio of 2way Western Electric theater speakers.